linux/samples
Daniel T. Lee 5a86381321 samples: bpf: fix: error handling regarding kprobe_events
Currently, kprobe_events failure won't be handled properly.
Due to calling system() indirectly to write to kprobe_events,
it can't be identified whether an error is derived from kprobe or system.

    // buf = "echo '%c:%s %s' >> /s/k/d/t/kprobe_events"
    err = system(buf);
    if (err < 0) {
        printf("failed to create kprobe ..");
        return -1;
    }

For example, running ./tracex7 sample in ext4 partition,
"echo p:open_ctree open_ctree >> /s/k/d/t/kprobe_events"
gets 256 error code system() failure.
=> The error comes from kprobe, but it's not handled correctly.

According to man of system(3), it's return value
just passes the termination status of the child shell
rather than treating the error as -1. (don't care success)

Which means, currently it's not working as desired.
(According to the upper code snippet)

    ex) running ./tracex7 with ext4 env.
    # Current Output
    sh: echo: I/O error
    failed to open event open_ctree

    # Desired Output
    failed to create kprobe 'open_ctree' error 'No such file or directory'

The problem is, error can't be verified whether from child ps
or system. But using write() directly can verify the command
failure, and it will treat all error as -1. So I suggest using
write() directly to 'kprobe_events' rather than calling system().

Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-11-23 22:39:09 +01:00
..
auxdisplay auxdisplay: Replace licenses with SPDX identifiers 2018-04-12 19:02:45 +02:00
bpf samples: bpf: fix: error handling regarding kprobe_events 2018-11-23 22:39:09 +01:00
configfs configfs: make config_item_type const 2017-10-19 16:15:15 +02:00
connector A relatively calm cycle for the docs tree again. 2017-11-13 08:25:06 -08:00
hidraw kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
hw_breakpoint perf: Add context field to perf_event 2011-07-01 11:06:38 +02:00
kdb kdb: Add kdb kernel module sample 2010-10-29 13:14:39 -05:00
kfifo kfifo: clean up example to not use page_link 2017-07-12 16:26:01 -07:00
kobject kobject: Remove redundant license text 2017-12-07 18:36:43 +01:00
kprobes arch: remove tile port 2018-03-16 10:56:03 +01:00
livepatch livepatch: Allow to call a custom callback when freeing shadow variables 2018-04-17 13:42:48 +02:00
mei mei: samples: fix a signedness bug in amt_host_if_call() 2018-10-02 15:39:59 -07:00
mic/mpssd Merge branch 'linus' into locking/core, to resolve conflicts 2017-11-07 10:32:44 +01:00
pktgen Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00
qmi samples: Introduce Qualcomm QMI sample client 2018-02-12 16:57:22 -08:00
rpmsg rpmsg: Allow callback to return errors 2016-09-08 22:15:25 -07:00
seccomp kbuild: Rename HOST_LOADLIBES to KBUILD_HOSTLDLIBS 2018-07-18 01:18:05 +09:00
statx kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
timers License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_events Merge branch 'for-linus' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2017-11-15 10:14:11 -08:00
trace_printk tracing: Add trace_printk sample code 2016-06-20 09:54:21 -04:00
uhid kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
v4l [media] media: v4l2-pci-skeleton: Fix error handling path in 'skeleton_probe()' 2017-10-04 16:55:02 -03:00
vfio-mdev vfio: add edid support to mbochs sample driver 2018-10-11 10:22:36 -06:00
watchdog License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig samples: disable CONFIG_SAMPLES for UML 2018-10-11 02:15:46 +09:00
Makefile remoteproc updates for v4.17 2018-04-10 12:09:27 -07:00